If the load is connected in wye (star) and it has a neutral, then the vectorial-difference of the phase currents will flow in the neutral and there will be no problem. On the other hand, if there is no neutral, then an unbalanced load would cause unbalanced phase voltages.
For a perfectly balanced load, with identical loads connected between each line conductor and the neutral conductor, there should be no neutral current. This is because the vector sum of three identical current, displaced by 120o, is zero.However, for an unbalanced load, there will always be a neutral current because the vector sum of the currents will not cancell.
As normally load distribution is done equally in all three phases, almost balanced current is drawn by load and current flow though neutral is very small when compared to the phase and hence difference in cable size is observed
Simply because it is cheaper. (You dont need the extra wire) However you can only use a 3 wire system if the load is a balanced load. If the load is not balanced you need the fourth wire (neutral/return) to take the out of balance current.
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
I think you probably mean is a neutral conductor necessary for a balanced star-connected load? If this is what you mean, then the answer is no, it isn't, as the phasor-sum of the phase currents will equal zero. Often, though, it is difficult to achieve a balanced load, so a neutral is then necessary, as it is needed to provide a return path for the unbalanced current -without this neutral, the phase voltages would change and become unbalanced.
By having a balanced load
Balanced load means no unbalanced currents, so the neutral current should be near zero.
if it is balanced then neutral current is zero (!,e iR=iY=iB).AnswerFor both a balanced and an unbalanced load, the neutral current will be the phasor sum of the line currents.
15 amps out and 15 amps back... unless there is a ground fault, but if that's the case you should shut down the device anyway.The answer above applies to the U.S. and Canada for 120 volt load or for a European 240V load.Note that in North America 240V it is different: For a US or Canada 240 volt load or a balanced three-phase load, there is no current flowing in the neutral.
If the load is connected in wye (star) and it has a neutral, then the vectorial-difference of the phase currents will flow in the neutral and there will be no problem. On the other hand, if there is no neutral, then an unbalanced load would cause unbalanced phase voltages.
For a perfectly balanced load, with identical loads connected between each line conductor and the neutral conductor, there should be no neutral current. This is because the vector sum of three identical current, displaced by 120o, is zero.However, for an unbalanced load, there will always be a neutral current because the vector sum of the currents will not cancell.
As normally load distribution is done equally in all three phases, almost balanced current is drawn by load and current flow though neutral is very small when compared to the phase and hence difference in cable size is observed
Simply because it is cheaper. (You dont need the extra wire) However you can only use a 3 wire system if the load is a balanced load. If the load is not balanced you need the fourth wire (neutral/return) to take the out of balance current.
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
If a neutral breaks the load will cease to operate.
The current carried by the neutral of a three phase four wire system is the un balanced current. If the three phase system was completely balanced on all three phases there would be no need for a neutral, eg a three phase motor. This neutral current will be less that the phase current so a reduction in the neutral size is allowed.